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Why NULL is not predefined by the compiler

This problem bothered me for a while. I have never seen another definition of NULL, it is always

#define NULL  ((void *) 0)

Is there any architecture where NULL is defined differently, and if so, why doesn't the compiler declare this for us?

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C 2011 Standard, online project

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I do not know the answer to this, but I think. In C, you usually do a lot of mallocs and therefore a lot of tests for returned pointers. Since malloc returns void *, and especially (void *) 0 after a failure, NULL is a natural thing to determine in order to verify the success of malloc. Since this is so important, other library functions also use NULL (or (void *) 0), such as fopen. In fact, everything the pointer returns.

Therefore, there is no reason to define this at the language level - it is simply a special pointer value that can be returned by so many functions.

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